US Patent 7847240 Mass spectroscopy system and method including an excitation gate

An ion extraction method and system includes: i) confining ions within an ion trap extending along a longitudinal axis; ii) exciting a subset of the ions to cause them to oscillate along at least one transverse coordinate; iii) after the transverse excitation, applying a first field and a second field in the region of the transverse excitation to move the excited ions towards one end of the ion trap and extract at least some of the excited ions at the end of the ion trap.